Battery system with parallel coupling protection

Abstract

A battery pack includes a housing having a positive terminal and a negative terminal. A battery cell is located within the housing and is selectively coupled to the positive terminal and to the negative terminal. A battery management system is located within the housing and configured to operate a first switch within the housing to selectively couple the battery cells and the positive terminal. The bleeder circuit is electrically coupled between the positive terminal and the negative terminal. The bleeder circuit includes a resistor and a second switch for selectively coupling the positive terminal to the negative terminal. The battery management system is configured to open the first switch and close the second switch, and measure a voltage drop across the resistor to detect the presence and type of a voltage source connected to the positive terminal.

Description

This application is a divisional application of the Chinese invention patent application with the application date of August 27, 2020, application number 202080066544.1, and invention name “Battery system with parallel connection protection”. CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Patent Application No. 62 / 892,803 filed on August 28, 2019, the contents of which are hereby incorporated by reference in their entirety. Background Art

[0002] The present invention relates generally to the field of indoor and outdoor power equipment, and particularly to the field of battery powered indoor and outdoor power equipment. Summary of the invention

[0003] At least one embodiment of the present disclosure is directed to a battery pack. The battery pack includes a housing having a positive terminal and a negative terminal. A battery cell is located within the housing and is selectively coupled to the positive terminal and to the negative terminal. A battery management system is located within the housing and is configured to operate a first switch within the housing to selectively couple the battery cells and the positive terminal. A discharge circuit is electrically coupled between the positive terminal and the negative terminal. The discharge circuit includes a resistor and a second switch for selectively coupling the positive terminal to the negative terminal. The battery management system is configured to open the first switch and close the second switch, and measure a voltage drop across the resistor to detect the presence and type of a voltage source connected to the positive terminal.

[0004] Another embodiment of the present disclosure relates to a battery pack. The battery pack includes a housing having a positive terminal and a negative terminal. A battery cell is located within the housing and is selectively coupled to the positive terminal and to the negative terminal. A battery management system is positioned within the housing and is configured to operate a main contactor switch and an auxiliary contactor switch to selectively couple the battery cells to the positive terminal. A discharge circuit extends between the positive terminal and the negative terminal. The discharge circuit includes a resistor and a discharge switch for selectively coupling the positive terminal to the negative terminal. The battery management system is configured to determine the presence of a voltage source on the positive terminal when the auxiliary contactor switch is in an open position. The battery management system is also configured to determine the type of the voltage source on the positive terminal when the auxiliary contactor switch is in a closed position and the discharge switch is in a closed position.

[0005] Another embodiment of the present disclosure relates to a battery system. The battery system includes a first battery pack and a second battery pack, each connected to a terminal bus. The first battery pack provides a voltage to the terminal bus. The second battery pack includes a discharge circuit, one or more contactors, one or more battery cells, and a battery management system. The one or more battery cells are selectively coupled to the terminal bus based on the position of the one or more contactors. The battery management system is configured to measure the voltage of the terminal bus coupled to the discharge circuit, the voltage corresponding to the output voltage of the first battery pack. The battery management system is also configured to determine whether the voltage of the terminal bus is less than a predetermined value. In response to determining that the voltage is less than the predetermined value, the battery management system is configured to connect the discharge circuit to the terminal bus to attempt to discharge the voltage of the terminal bus. In response to determining that the voltage of the terminal bus is not discharged by a predetermined threshold amount, the battery management system determines whether the voltage of the terminal bus is within a lockout voltage range. If the battery management system determines that the voltage of the terminal bus is within the lockout voltage range, the battery management system couples the battery cell to the terminal bus by closing the one or more contactors.

[0006] Another embodiment of the present disclosure relates to a battery system. The battery system includes a plurality of battery packs in a parallel configuration, and an independent battery pack. The independent battery pack includes a discharge circuit, a main contactor, an auxiliary contactor, one or more battery cells, and a battery management system. The battery management system is configured to measure the voltage of a terminal bus coupled to the discharge circuit and measure the voltage between the main contactor and the auxiliary contactor. The battery management system is further configured to delay the start of a test coupling the independent battery pack to the plurality of battery packs based on a preprogrammed value. The battery management system is further configured to turn on the discharge circuit of the independent battery pack in an attempt to discharge the voltage of the terminal bus. In response to the voltage of the terminal bus being discharged at a threshold amount (as detected by the battery management system), the battery management system is configured to couple the independent battery pack to the plurality of battery packs.

[0007] Another embodiment of the present disclosure relates to a method for coupling a battery pack in parallel to a common terminal bus. The method includes measuring the voltage of a terminal bus coupled to a discharge circuit of an independent battery pack. The independent battery pack includes the discharge circuit, one or more contactors, one or more battery cell assemblies, and a battery management system. The method also includes delaying the start of a test of coupling the independent battery pack to multiple battery packs based on a predetermined value. The method also includes engaging the discharge circuit of the independent battery pack to attempt to discharge the voltage of the terminal bus. The method also includes coupling the independent battery pack to the multiple battery packs in response to the voltage of the terminal bus being discharged by a threshold amount. The multiple battery packs are arranged in a parallel configuration. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The present disclosure will be more fully understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0009] Figure 1 is a schematic diagram of a battery system having battery packs connected in a parallel configuration according to an exemplary embodiment;

[0010] Figure 2 yes Figure 1 A schematic diagram of a battery system, wherein the battery pack is in an ideal nominal state;

[0011] Figure 3 yes Figure 1 A schematic diagram of a battery system in which the battery pack is in a non-ideal state;

[0012] Figure 4 yes Figure 1 Schematic diagram of a battery system with other case scenarios where the battery pack is in a non-ideal state;

[0013] Figure 5 yes Figure 1 A schematic diagram of a battery system in which the battery pack is in a non-ideal state and a parallel connection process is shown;

[0014] Figure 6 yes Figure 1 An internal schematic diagram of a battery pack in a battery system and a discharge circuit for a parallel connection process;

[0015] Figure 7 yes Figure 1 In the battery system one A schematic diagram of the interior of the battery pack showing the functional schematic of the discharge circuit;

[0016] Figure 8 is a flowchart of a process for using Figure 7 The bleeder circuit discharges to determine the battery pack and Figure 1 The ability to connect other battery packs in parallel with the battery system;

[0017] Fig. 9 According to some embodiments, Figure 8 The process continues with a flowchart of the process for using Figure 7 The discharge circuit of the battery pack is discharged to determine the ability of the battery pack to be connected in parallel with other battery packs;

[0018] Fig.10 is used to make Figure 1 A sequencing table used in the parallel process of discharging a battery system;

[0019] Fig.11 yes Figure 1An internal schematic diagram of one of the battery packs in the battery system of FIG. 1 , showing another embodiment of the functional schematic diagram of the discharge circuit;

[0020] Fig.12 is a flowchart of a process for using Fig.11 The bleeder circuit discharges to determine the battery pack and Figure 1 The ability to connect other battery packs in parallel with the battery system;

[0021] Fig.13 According to some embodiments, Fig.12 The process continues with a flowchart of the process for using Fig.11 The bleeder circuit discharges to determine the battery pack and Figure 1 The ability to connect other battery packs in parallel with the battery system;

[0022] Fig.14 is used to make Figure 1 An example of a discharge circuit sequence timeline for discharging one of the battery packs in the battery system;

[0023] Fig.15 is used to make Figure 1 An example of a discharge circuit sequence for a parallel process of discharging one of the battery packs in a battery system having only one battery and no terminal energy storage device;

[0024] Fig.16 is used to make Figure 1 Another example of a discharge circuit sequence for a parallel process of discharging one of the battery packs in a battery system having only one battery and a terminal energy storage device;

[0025] Fig.17 is used to make Figure 1 Another example of a discharge circuit sequence for a parallel process of discharging one of the battery packs in a battery system having only one battery and a terminal energy storage device;

[0026] Fig.18 is used to make Figure 1 An example of a discharge circuit sequence for a parallel process of discharging one of the battery packs in a battery system having two or more batteries and no CANbus communication;

[0027] Fig.19 is used to make Figure 1 Another example of a discharge circuit sequence of a parallel process of discharging one of the battery packs in a battery system having two or more batteries and no CANbus communication;

[0028] Fig. 20 is used to make Figure 1 A sequencing table used in the parallel process of charging the battery system;

[0029] Fig.21 is a flowchart of a process for using Figure 7 The bleeder circuit is charged to determine the battery pack and Figure 1 The ability to connect other battery packs in parallel with the battery system;

[0030] Fig. 22 According to some embodiments, Fig.21 The process continues with a flowchart of the process for using Figure 7 The bleeder circuit is charged to determine the battery pack and Figure 1 The ability to connect other battery packs in parallel with the battery system;

[0031] Fig.23 is a flowchart of a process for using Fig.11 The bleeder circuit is charged to determine the battery pack and Figure 1 The ability to connect other batteries in parallel with the battery system; and

[0032] Fig.24 According to some embodiments, Fig.23 The process continues with a flowchart of the process for using Fig.11 The bleeder circuit is charged to determine the battery pack and Figure 1 The ability to connect other battery packs in parallel to the battery system. DETAILED DESCRIPTION

[0033] Before turning to the drawings showing exemplary embodiments in detail, it should be understood that the present application is not limited to the details or methods set forth in the description or shown in the drawings. It should also be understood that the terminology is used for descriptive purposes only and should not be considered as limiting.

[0034] Referring to the accompanying drawings in general, the battery system described herein allows multiple battery packs to be arranged in a parallel configuration so that significant inrush or latching current is avoided, regardless of whether the battery packs are currently in the same state of charge or the same output voltage. Conventional batteries (e.g., lithium-ion, lead-acid) connected in parallel to a common terminal bus attempt to immediately balance the state of charge between the batteries on the bus. If the difference in the state of charge between the batteries is significant, very high currents may be experienced. Lead-acid batteries have very high internal resistance and are better able to withstand charge balancing because the current experienced by the battery is much lower due to Ohm's law. However, because lithium-ion batteries traditionally have much lower internal resistance than lead-acid batteries, lithium-ion batteries are less equipped to handle the imbalance of the state of charge. In some cases, the difference in the state of charge between the batteries along the common terminal bus may result in a current of 3000A or more in the lithium-ion battery, which may cause significant damage to the battery itself. The disclosed battery system is designed to protect the battery pack and equipment from experiencing these large inrush or latch-up currents that could be hazardous to the health of the battery pack, equipment, and the entire battery system by monitoring the terminal bus and connecting the terminal bus only after the battery pack has determined that it is safe to connect the terminal bus.

[0035] The battery packs within the battery system are designed so that each battery pack can detect the presence and type of equipment connected to the terminal bus before the battery cells within the battery pack are engaged to the common terminal bus. In order to monitor the terminal bus, the battery pack includes a battery management system that monitors the voltage and / or current along the terminal bus. The battery management system operates and monitors the discharge circuit within the battery pack to detect the presence of charging along the terminal bus. Initially, the battery management system determines whether there is a voltage on the terminal bus. If the battery management system does not detect the voltage along the terminal bus, the battery management system allows the battery pack (e.g., the battery cells within the battery pack) to engage the terminal bus because there is no risk of detecting an overcurrent condition. If the battery management system does detect the voltage along the terminal bus, the battery management system will try to identify the type of power supply providing the voltage on the terminal bus. In order to identify the voltage source type, the battery management system connects the terminal bus to the discharge circuit within the battery pack and monitors the voltage drop across the discharge circuit over a period of time. If the detected voltage source is provided by the equipment itself (e.g., by a capacitor on a motor of a power equipment that has stored energy, etc.), the voltage detected by the battery management system will decrease over time because the terminal bus is effectively "erased" of any charge. The current passes through the terminal bus to the bleeder circuit and then to ground as the energy source dissipates. Considering the exponential decay nature of capacitive energy sources, the battery management system determines that there are no other batteries on the terminal bus based on the rate of change of the voltage detected across the bleeder circuit. Therefore, the battery management system again determines that it is safe for the battery to engage the terminal bus and coordinates the internal switches to establish an electrical connection between the battery cells within the battery pack and the terminal bus.

[0036] If the battery management system does not detect that the voltage source is depleted over time, the battery management system knows that the voltage source may be another battery. The battery management system then uses the discharge circuit and associated sensors to measure the voltage on the terminal bus. If the difference between the voltage on the terminal bus and the voltage within the battery pack is within a predetermined range (e.g., + / -1.00V), the battery management system will determine that it is also safe for the battery to engage the terminal bus because the difference between the voltage within the battery pack and the voltage along the terminal bus will not cause a significant inrush or latching current that will damage the battery pack. The battery management system will once again coordinate the internal switches to couple the battery cells to the terminal bus to allow the battery pack to discharge through the terminal bus. Each battery within the battery system can include a battery management system to monitor the charge on the terminal bus to determine whether it is safe for the battery to engage the terminal bus and release energy so that the battery engagement process can occur sequentially when all batteries are in approximately equal states of charge.

[0037] If an unsafe condition is detected, the battery system (e.g., a battery management system within a battery pack) will also prevent the battery from engaging the terminal bus. For example, if the battery management system detects the presence of another battery along the terminal bus (e.g., because the voltage has not been discharged over time, indicating a capacitive energy source), the battery management system detects the battery voltage within the battery pack and compares it to the voltage along the terminal bus. If the difference between the two exceeds a predetermined range (e.g., + / -1.00V), the battery management system will understand that engaging the battery cell to the terminal bus may cause damage to the battery pack. Therefore, the battery management system will disconnect the internal switch to prevent communication between the battery cell and the terminal bus. The battery management system will continue to monitor the voltage along the terminal bus until it is eventually detected that (1) there is no longer another voltage source along the terminal bus or (2) the voltage source along the terminal bus is within a predetermined allowable range and it is now safe to engage the terminal bus in a parallel configuration. Using the battery system described herein, the battery pack avoids potentially destructive currents that may be caused by the battery blindly engaging the terminal bus in a parallel arrangement, regardless of whether there are other voltage sources along the terminal bus.

[0038] The parallel battery pack configuration is commonly used in battery assemblies for various types of indoor and outdoor power equipment, as well as for portable worksite equipment and military vehicle applications. Outdoor power equipment includes lawn mowers, riding tractors, snow blowers, pressure washers, tillers, wood splitters, zero-turn radius mowers, walk-behind mowers, riding mowers, upright mowers, road surface preparation equipment, industrial vehicles such as forklifts, utility vehicles, commercial lawn equipment such as blowers, vacuum cleaners, debris loaders, seeders, leaf cleaners, aerators, sod cutters, brush mowers, portable generators, etc. Indoor power equipment includes floor sanders, floor shock absorbers and polishers, vacuum cleaners, etc. Portable worksite equipment includes portable lighting, mobile industrial heaters, and portable light stands. Military vehicle applications include installing the battery system on all-terrain vehicles (ATVs), utility mission vehicles (UTVs), and light electric vehicle (LEV) applications. The parallel arrangement of battery packs is particularly useful and common in situations where the battery packs do not have predetermined or designated equipment. Because the same battery pack can be used to power several different powered equipment, the ability to determine the presence of other voltage sources along the terminal bus becomes particularly useful.

[0039] refer to Figure 1According to an exemplary embodiment, the battery system 100 is shown as having battery packs connected in a parallel configuration. The battery system 100 can have up to four different battery packs 102, 104, 106, 108 connected together in parallel, wherein each positive terminal of the battery packs 102, 104, 106, 108 is connected to a positive terminal bus 122, and each negative terminal of the battery packs 102, 104, 106, 108 is connected to a negative terminal bus 124. A variety of different battery pack arrangements can also be used. For example, the battery system 100 can have only a single battery pack 102, or can have a battery pack 104, a battery pack 106, and a battery pack 108 connected in a parallel configuration. The battery system 100 may have more than four different battery packs connected in parallel, such as sixteen or more battery packs. The negative terminal bus 124 is connected to a common ground so that the battery packs 102, 104, 106, and 108 are all grounded together. In some embodiments, the battery pack 102 and other battery packs in the system 100 are lithium-ion batteries. In other embodiments, the battery pack 102 and other battery packs in the system 100 are different battery types (e.g., lead-acid, lithium polymer, nickel-cadmium, etc.).

[0040] In a typical case, each battery pack 102, 104, 106, 108 in the battery system 100 is connected to a 29-bit controller area network bus (CANbus) network for sending and receiving communications from other battery packs. CANbus link 110, CANbus link 112, and CANbus link 114 are complete to allow network communications between battery packs 102, 104, 106, 108 of the battery system 100. Alternatively, other digital communication protocols can be used instead of CANbus communication. For example, the digital communication protocol can use one or more of I2C, I2S, serial, SPI, Ethernet, 1-Wire (single bus), etc. In addition, each battery pack 102, 104, 106, 108 in the battery system 100 can be connected to the same charge enable signal and the same discharge enable signal as each other battery pack. For example, the discharge enable signal 116 is connected to the discharge enable signal 118 and the discharge enable signal 120.

[0041] refer to Figure 2 According to an exemplary embodiment, the battery system 200 is shown as having a Figure 1The battery packs in an ideal nominal state connected in a parallel configuration. In an ideal state, each battery pack in the battery system 200 is charged to the same amount and therefore has the same state of charge (SOC). For example, battery pack 202, battery pack 204, battery pack 206, and battery pack 208 each have a state of charge of 75% of the full charge capacity. In addition, in this state, each battery pack in the battery system 200 is also connected to the CANbus network (e.g., CANbus link 210, CANbus link 212, and CANbus link 214 are working normally). Battery pack 202 can then communicate with battery pack 204, battery pack 206, and battery pack 208 via the CANbus network. The communication may include, for example, messages related to the charging of battery pack 202 or the health of the battery cells within battery pack 202. In addition, under nominal conditions, the battery system 200 is configured such that each battery pack 202, 204, 206, 208 receives a charge or discharge enable signal (via discharge enable signals 216, 218, 220) simultaneously with the other battery packs in the battery system 200. Similar to the battery system 100, the battery system 200 shows that each battery pack 202, 204, 206, 208 is electrically coupled to each of the positive terminal bus 222 and the negative terminal bus 224.

[0042] refer to Figure 3 , battery system 300 is shown having battery pack 302, battery pack 304, battery pack 306, and battery pack 308 connected in a parallel configuration. Figure 1The battery system 100 shown and described, the battery system 300 is shown as being in a non-ideal state. A non-ideal system state will occur when any or all of the following occur: the battery packs 302, 304, 306, 308 within the battery system 300 have a unique charge state compared to any of the other battery packs; one or more of the battery packs 302, 304, 306, 308 are disconnected from the 29-bit CANbus network; and / or any of the battery packs 302, 304, 306, 308 receives a corresponding charge or discharge enable signal at a time separate from any of the other battery packs 302, 304, 306, 308. For example, if the discharge enable signal 316 for the battery pack 302 experiences a communication error and does not work properly, or if the CANbus link 314 is disconnected and no messages are received or sent across the link 314, the battery system 300 is in a non-ideal state. A battery system having any of these conditions is undesirable due to the problems caused by having a non-ideal system state. For example, when the discharge enable signals 316 , 318 , 320 are not functioning properly, different discharge rates may occur between the battery packs 302 , 304 , 306 , 308 and the positive terminal bus 322 or the negative terminal bus 324 to which each battery pack 302 , 304 , 306 , 308 is coupled.

[0043] The non-ideal state of having a unique state of charge prevents two or more battery packs from engaging the positive terminal bus at the same time because the different states of charge can generate extremely high latching currents. If the latching current is not reduced or eliminated, the latching current may be detrimental to the health of the battery pack. If the battery packs 302, 304, 306, 308 within the battery system 300 are disconnected from the CANbus network and do not receive communications from other battery packs 302, 304, 306, 308, the battery pack may not recognize the presence of other battery packs 302, 304, 306, 308 within the battery system 300 and may discharge in different ways. In a conventional system, if a disconnected battery pack attempts to engage the positive terminal bus (e.g., the positive terminal bus 322) to which other battery packs are connected, a very high and potentially destructive latching current may be generated due to an attempt to connect the positive terminal bus 322. Furthermore, if a battery pack (e.g., battery pack 302) receives a charge or discharge enable signal at a different time than any of the other battery packs (e.g., battery pack 304, battery pack 306, and / or battery pack 308), battery pack 302 may attempt to engage the positive terminal bus 322 while the other battery packs are connected. Similarly, if any two or more battery packs receive an enable signal to engage at exactly the same time, an attempt to engage the positive terminal bus 322 may result in a very high latch-up current, which may damage both battery packs.

[0044] Reference now Figure 4 , the battery system 400 is shown with battery pack 402, battery pack 404, battery pack 406, and battery pack 408 in a parallel configuration, which presents another non-ideal case scenario system state. In this case, the battery packs 402, 404, 406, 408 in the battery system 400 each have a SOC that is significantly different from the other SOCs, each battery pack is disconnected from the CANbus communication network, and each battery pack 402, 404, 406, 408 receives a discharge enable signal at exactly the same time as the other battery packs. Figure 4 This scenario is shown occurring when battery pack 402 has an 80% SOC, battery pack 404 has a 40% SOC, battery pack 406 has a 10% SOC, and battery pack 408 has a 90% SOC, CANbus link 410, CANbus link 412, and CANbus link 414 all experience complications and do not function, and discharge enable signal 416, discharge enable signal 418, and discharge enable signal 420 all occur at exactly the same time.

[0045] Figure 5 The paralleling process during discharge mode is shown, which can solve the non-ideal state of the battery pack. Figure 4 Similarly, the battery system 500 is shown with all battery packs 502, 504, 506, 508 in a non-ideal state. The paralleling process attempts to correct for the non-ideal state during the discharge mode, where the battery 508 attempts to engage other battery packs 502, 504, 506. During this process, two different hardware-based processes may occur in the case where the battery system 500 is in a non-ideal state. First, a battery pack (e.g., battery pack 508) in the battery system 500 can determine whether the positive terminal bus 510 has any other energy storage devices connected to it, such as another battery pack 502, 504, 506, a capacitor, or a capacitor "bank" (i.e., multiple capacitors in series and / or parallel). Then, if another battery pack 502, 504, 506 is connected to the positive terminal bus 510, the battery pack 508 in the battery system 500 can determine whether it is safe to engage the positive terminal bus 510. Each battery management system having battery packs 502, 504, 506, 508 will execute to protect its own battery cells and to protect components of the battery pack (e.g., wire bonds, wiring, contactors, etc. within the battery pack), where the overall ultimate goal of each battery pack is to supply power to a machine (e.g., outdoor power equipment, indoor power equipment, portable worksite equipment, military vehicle applications, etc.) in a safe manner.

[0046] Reference now Figure 6 , showing a battery pack 600 and for performing Figure 5An internal view of a bleeder circuit for a parallel process of a battery pack 600. In some embodiments, the battery pack 600 includes a main contactor 602, an auxiliary contactor 604, a bleeder circuit 608, a battery management system (BMS) 614, and a battery cell 618. The main contactor 602 and the auxiliary contactor 604 are electrical switches (e.g., MOSFETs, solid-state relays, transistors, etc.) that can be turned on to connect to a positive terminal bus (such as the positive terminal bus 618). In some embodiments, a load 606 is electrically coupled between the positive terminal bus 618 and the negative terminal bus 620. The load 606 can be a machine to which the BMS 614 supplies power, such as a motor of an outdoor power equipment. The bleeder circuit 608 can be connected from the positive terminal bus 618 to a common ground at the negative terminal bus 620, as shown in reference Figure 1 The bleeder circuit 608 may be designed to include a load 610 and a solid-state relay or bleeder switch 612. The load 610 may be a load "group" including other components, or may be a bleeder resistor that has a dual purpose as a heating element for a battery internal heater pad (not shown) used in a cold-resistant battery pack. In other embodiments, the bleeder circuit 608 includes other mechanical components to include a load that can be connected to the BMS 614, the positive terminal bus 618, and the ground at the negative terminal bus 620.

[0047] The bleeder circuit 608 can determine whether the positive terminal bus 618 is connected to another energy storage device (e.g., another battery pack or a capacitor). Inside the battery pack 600 at the BMS 614 level, the operation of the bleeder circuit 608 begins with the switching device (e.g., solid-state relay 612) attempting to "bleed" the voltage at the positive terminal bus 618 (if there is a voltage) through the load 610 to ground at the negative terminal 622. The bleeder circuit 608 then monitors how fast the voltage decays. For example, if the voltage at the positive terminal bus 618 is 40V and the bleeder circuit 608 finds that the voltage has dropped to 30V, there is a 25% change in voltage from the bleeder circuit 608. If the rate of voltage decay observed by the bleeder circuit 608 is very high (e.g., 90% or more), a capacitive energy storage device is likely present and it is safe for the battery pack 600 to be connected in parallel to the battery system (e.g., battery system 100, 200, 300, 400). However, if the voltage decay rate is very low (e.g., less than 10%), meaning that there is no change or very little change in the terminal bus voltage across the bleeder circuit 608, then another battery pack or energy storage device (e.g., a 12V lead-acid battery or an unauthorized charger) is connected to the positive terminal bus 618 and it may be unsafe to connect the battery pack 608 in parallel to the existing battery system.

[0048] refer to Figure 7, a functional schematic diagram 700 of a bleeder circuit 608 in a battery pack 600 is shown. A BMS 714 (which may be similar to BMS 614) may be connected to a positive terminal bus 618 via a main (terminal) voltage sense 704. A future output 710 from the BMS 714 may be connected to a solid-state relay 708 (e.g., a field effect transistor (FET), a transistor, an insulated gate bipolar transistor (IGBT), etc.) and the positive terminal bus 618 via a bleeder resistor 706. The bleeder circuit 608 may bleed the voltage at the positive terminal bus 618 to a common ground at the negative terminal bus 620 via the bleeder resistor 706 and the solid-state relay 708. In some embodiments, the bleeder resistor 706 has a resistance value of 10 ohms. The BMS 714 may be connected to an internal battery pack current sensor 712, which is connected to the negative terminal bus 620 to be grounded. The internal battery pack current sensor 712 may be, for example, a shunt resistor. The battery cells 716 may be connected at their respective positive terminals to the main contactor 702, at their respective negative terminals to a common ground at the negative terminal bus 620, and to the BMS 714 so that the battery management system knows the status of the battery cells 716. The main contactor 702 connects the battery cells 716 to the positive terminal bus 618 when turned on. In other embodiments, the battery pack 600 also includes a pre-charge relay (e.g., Fig.11 ), which, in addition to the function of the bleeder circuit 608, can also help protect the main contactor 702 (or main contactor 1102). The pre-charge relay can slow down the change in voltage over time to help prevent inrush current that can damage battery pack components.

[0049] refer to Figure 8, an automatic process 800 is shown for determining the ability of a battery pack (e.g., battery pack 102) to be engaged in parallel with other battery packs (e.g., battery packs 104, 106, 108) of a battery system (e.g., battery system 100, 200, 300, 400, etc.) using a bleeder circuit (e.g., bleeder circuit 608) to discharge. The process 800 may be performed in part by an application associated with the BMS 714. The process 800 may be used to prevent damage to the battery pack due to high inrush current (e.g., 3000 amperes of current) when engaging a battery system having a parallel configuration. The process 800 begins at step 802, which performs a CAN source address request process to determine whether there are other batteries on the CANbus network. Step 802 may occur at a predetermined time (such as 1.5 seconds) from the input of a discharge enable signal. The predetermined time from the input of the discharge enable signal may be exactly the same amount of time, regardless of whether any other batteries are found to be present. The presence or absence of any other CAN-enabled batteries is recorded and potentially performed by the battery system (e.g., if other batteries are found, digital communications can take precedence over hardware-level paralleling schemes and the batteries can immediately engage the terminals). Next, at step 804, process 800 includes measuring the main contactor 702 voltage sensing potential, which corresponds to the terminal bus voltage. Then at step 806, the BMS 714 determines whether the measured voltage is greater than or less than a predetermined value. If the BMS 714 finds that the voltage is greater than the predetermined value, then at step 808, the BMS 714 waits a predetermined time and then remeasures the voltage. Next, at step 810, the BMS 714 determines whether the remeasured new voltage is now less than a predetermined value.

[0050] If the new voltage value is still too high, the BMS 714 issues a soft fault at step 818. For example, if the predetermined value is 60V and the remeasured value is still greater than 60V after waiting 10 seconds from the first measurement, the BMS 714 may issue a soft fault indicating that a "high sub-bus voltage" exists.

[0051] Alternatively, if the voltage is found to be less than the predetermined value in step 806, then at step 812, process 800 postpones the time based on the measured battery voltage according to the discharge sequencing table. After the delay time starts from step 812, at step 814, the BMS turns on the bleeder circuit (e.g., bleeder circuit 608) and measures the percentage change in the terminal bus voltage. Once the change in the terminal bus voltage is measured, process 800 ends at step 816. In the event that process 800 ends, process 900 can begin, such as Fig. 9 as shown in .

[0052] refer to Fig. 9, shows a process 900 according to an exemplary embodiment, which is used to determine the ability of a battery pack to be connected in parallel with other battery packs using a bleeder circuit discharge. Process 900 can start at the end of process 800 (e.g., starting from box 816). In some embodiments, process 900 starts at step 902, that is, BMS 714 determines whether the percentage change of the terminal bus voltage after the bleeder circuit 608 "bleeds" the voltage is greater than a predetermined value. If BMS 714 detects that the percentage change is greater than a predetermined value (e.g., above 90%), process 900 proceeds to step 904, where the battery pack (by engaging the main contactor) engages the terminal bus and changes the mode to "discharge". For example, if the percentage change is greater than 15% within 100 milliseconds (ms), the main contactor 702 is turned on, and the battery pack 600 engages the positive terminal bus 122 and enters the "discharge" mode.

[0053] Conversely, if the BMS 714 detects that the percentage change is less than a predetermined value in step 902, the process 900 continues to step 906, where the BMS 714 causes the bleeder circuit to continue to operate for an additional predetermined time. In some embodiments, the predetermined value is 15% within 100 ms, and the additional predetermined time that the bleeder circuit operation continues is 50 ms, giving a total amount of time of 150 ms.

[0054] After the additional predetermined time has passed, at step 908, the BMS 714 may again determine whether the percentage change is now greater than a predetermined value. If, after the additional time, the percentage change is high enough, the process 900 proceeds to box 904 and the battery pack engages the terminal bus. If the percentage change is still not high enough after step 906, the process 900 proceeds to determine whether the battery pack is within the lockout voltage at step 910. If the battery pack is not within the lockout voltage, at step 912, the BMS 714 changes the mode of the battery pack to "standby discharge" in the communication mode. However, if the battery pack is within the lockout voltage, the process 900 proceeds to step 914, where the battery pack engages the terminal bus. For example, if the battery pack 600 is within the lockout voltage (e.g., as determined by the BMS 714), the main contactor 702 is turned on, and the battery pack 600 engages the positive terminal bus 122 because another battery is present and within the lockout range.

[0055] Fig.10 The parallel connection process of the battery system 100 (such as reference Figure 8800) used in the discharge sorting table 1000. In some embodiments, the discharge sorting table 1000 includes a low voltage region 1002, a voltage range column 1006, a delay column 1004, and a sequence number column 1008. The low voltage region 1102 highlights the voltage range that falls below the required minimum activation (start) threshold voltage (e.g., below 41.8V). The voltage range column 1006 can be used during step 812 in the process 800 to find the delay (in ms) corresponding to the measured terminal bus voltage value. For the discharge sorting table 1000, the standard latching voltage is set to + / -1.00V, and the incremental delay time of the next sequence is increased by 250ms. In some embodiments, when the fourth battery pack attempts to engage, the blind (no CANbus communication network) hardware parallel system has three battery packs that have been combined (i.e., locked) together. For this example, a differential voltage of 1.00V can cause a transient balancing current of 40A, which is still safe for the engaged battery pack to experience.

[0056] refer to Fig.11 Another battery pack 1100 that can be used for the battery system 100 is shown. The battery pack 1100 includes a BMS 1118, which can be connected to the positive terminal bus 1124 through the main (i.e., terminal) voltage sense 1106. The BMS 1118 can be connected between the main contactor 1104 and the auxiliary contactor 1102 through the auxiliary voltage sense 1114. The auxiliary voltage sense 1114 can be pulled to the ground internally via a high resistance resistor to avoid the holding voltage in the circuit. The discharge signal 1116 can be connected to the switching device 1110, which is grounded to the common ground at the negative terminal 1126. In some embodiments, the discharge signal 1116 is connected to the switching device 1110 and between the auxiliary contactor 1102 and the primary contactor 1104 through the discharge resistor 1108. The discharge resistor 1108 can have a resistance in the range of 1 to 100 ohms (e.g., the resistor 1108 is a 20 ohm resistor). The BMS 1118 may be connected to an internal battery pack current sensor 1120 which is then connected to ground via the negative terminal bus 124 and may be resistively coupled to a reference Figure 7The internal battery pack current sensor 712 described above is similar or identical. The internal battery pack current sensor 1120 can be a shunt resistor, or can be another type of sensor (e.g., a Hall effect sensor) in place of a shunt resistor. The machine (i.e., load) 1112 can be a variety of devices, such as controllers for outdoor power equipment, indoor power equipment, portable worksite equipment, military vehicle applications, etc. The battery cells 1122 can be connected to the auxiliary contactor 1102 at their respective positive terminals, to a common ground at the negative terminal bus 1126 at their respective negative terminals, and to the BMS1118 so that the battery management system knows the status of the battery cells 1122 within the battery pack 600. When both the auxiliary contactor and the primary contactor are turned on, the battery cells 1122 can be connected to the positive terminal bus 1124. As described above, the battery pack 1100 may include a pre-charge relay 1128 positioned in series with the battery cell 1122, the discharge switch device 1110, the internal battery pack current sensor 1120, and the negative terminal of the battery cell (which may be coupled to the negative terminal bus 1126).

[0057] refer to Fig.12 , an automatic process 1200 for determining the ability of a battery pack to be connected in parallel with other battery packs using a bleeder circuit discharge is shown. Process 1200 is shown as including performing a CAN source address request process at step 1202 to determine whether there are other batteries on the CANbus network. Step 1202 may occur at a predetermined time (such as 1.5 seconds) from the start of the discharge enable signal input, which may be exactly the same amount of time regardless of whether any other batteries are found to be present. The presence or absence of any other CAN-enabled battery is recorded (e.g., by BMS1118). At step 1204, the voltage sensing potential (i.e., terminal bus voltage) of the main contactor 1104 is measured (e.g., by BMS1118). In some embodiments, at step 1206, BMS 1118 determines whether the measured voltage is greater than or less than a predetermined value. If the voltage is found to be greater than a predetermined value in step 1206, BMS1118 proceeds to step 1210 and waits for a predetermined time before restarting the process to remeasure the voltage.

[0058] At step 1222, after waiting for the predetermined period of time, the BMS1118 determines whether the remeasured new voltage is now less than the predetermined value. If the new voltage value is still greater, a soft fault is issued at step 1224. For example, if the predetermined value is 60V or greater, and the remeasured value is still greater than 60V after waiting for 10 seconds and restarting the process, the BMS1118 can issue a soft fault indicating that there is a "high-side bus voltage". Conversely, if the voltage is found to be less than the predetermined value in step 1206, the process 1200 proceeds to step 1208, where the BMS1118 measures the auxiliary (contactor) voltage sensing potential. At step 1212, the BMS1118 checks whether the measured auxiliary voltage is zero, which may indicate a problem with the main contactor. If the auxiliary voltage is not 0V, the BMS1118 issues a soft fault in step 1224, indicating that there may be a main contactor fault.

[0059] However, if the auxiliary voltage is 0V, the process 1200 continues to step 1214, where the BMS1118 turns on the bleeder circuit (e.g., bleeder circuit 608) and measures the current of the battery pack for a predetermined time. After measuring the battery pack current, at step 1216, the BMS1118 determines whether the current exceeds a predetermined amount. For example, the battery current of 10.0ms can be measured and the current is evaluated to see if the absolute value of the current is greater than 1A current. If the battery pack current exceeds the predetermined amount, the process 1200 proceeds to step 1224 again, where the BMS issues a soft fault, indicating that there may be an auxiliary contactor and / or auxiliary voltage sensing fault. Conversely, if the current measured in step 1214 is lower than the predetermined amount, the process 1200 continues to step 1218, where the main contactor is turned on, and the battery pack current is measured again for a predetermined time. After step 1218, the process 1200 can continue to step 1220, which corresponds to the start of process 1300.

[0060] refer to Fig.13, shows an automatic process 1300 for determining the ability of a battery pack to be connected in parallel with other battery packs using a bleeder circuit discharge. Process 1300 begins at step 1302, where the BMS 1118 determines whether the current exceeds a predetermined amount. For example, the battery current may have a predetermined limit of 1A. Therefore, the BMS 1118 needs to verify that the absolute value of the current is not greater than the 1A current. If the BMS 1118 detects that the battery pack current exceeds the predetermined amount, the process 1300 proceeds to step 1318, and the BMS 1118 issues a soft fault, indicating that there may be a bleeder circuit 608 fault. If the current measured in step 1302 is lower than the predetermined amount, the process 1300 proceeds to step 1304, and the time is delayed by a predetermined amount of time determined by a discharge ranking table (e.g., discharge ranking table 1000). The predetermined amount of time may be based on the voltage of the battery pack. Once the predetermined time period has passed, the BMS 1118 may turn on the bleeder circuit and measure the percentage change in the terminal bus voltage (i.e., the primary voltage sensing potential) at step 1306. If the percentage change in the terminal bus voltage after operating the bleeder circuit 608 as determined by the BMS 1118 at step 1308 is greater than a predetermined value, then at step 1310, the BMS 1118 may prompt the battery pack to engage the terminal bus by engaging the auxiliary contactor and changing the mode of the battery pack to "discharge". In some embodiments, if the percentage changes by more than 15% within 100 ms, the auxiliary contactor 1102 is turned on and the battery pack 600 engages the positive terminal bus 122 and enters a "discharge" mode.

[0061] However, if the percentage change is found to be below a predetermined value at step 1308, the process 1300 proceeds to step 1312, where the BMS 1118 causes the bleeder circuit to continue to operate for an additional predetermined time. In some embodiments, the predetermined value is 15% within 100 ms, and the additional predetermined time that the bleeder circuit operation continues is 50 ms, giving a total amount of time of 150 ms. At step 1314, the BMS 1118 determines whether the percentage change is now greater than the predetermined value. If the percentage change is determined to be high enough after the additional bleeder circuit operation at steps 1312 and 1314, the process 1300 proceeds to step 1310, where the BMS 1118 causes the auxiliary contactor 1102 to engage the terminal bus (e.g., the positive terminal bus 122) and changes the mode to "discharge" at step 1310. However, if the percentage change is too low even after the increased operating time of the bleeder circuit, the process 1300 proceeds to step 1316 by changing the mode of the battery pack to "standby discharge" in the communication mode. In some embodiments, the goal of parallel connection during discharge mode is to have all battery packs engage the positive terminal bus within 3 seconds. In summary, in discharge mode, the battery comes to the common positive terminal bus (e.g., positive terminal bus 122) using timing based on the voltage of the individual battery packs, and then attempts to discharge the voltage of the terminal bus. If the battery can discharge the voltage, the battery can be engaged, but if the discharge circuit does not discharge the voltage, the battery can determine whether it is safe to engage. If the battery has determined that the engagement is safe, the battery can engage the parallel configuration. Otherwise, if the engagement is not safe, the battery can wait to engage and continue to monitor the voltage on the terminal bus until it is safe to engage. This can be determined using some or all of the same steps as in processes 1200 and 1300, repeated until it is found that the battery can be safely engaged after successfully discharging the voltage of the terminal bus.

[0062] refer to Fig.14 , showing a method for Figure 1 100 , as shown in FIG. 101 . An example of a discharge circuit timeline sequence for discharging one of the battery packs in the battery system of FIG. 100 . All battery packs (e.g., battery packs 102 , 104 , 106 , 108 ) receive the same discharge enable signal at the same time. According to the discharge sequence table 1000 , as shown in FIG. Fig.10As shown, the first battery pack 1418 of 58.1V has a specified delay time of 200ms before starting the discharge test using its discharge circuit (e.g., discharge circuit 608), and the delay 1402 is shown in gray. Because battery packs 1420, 1422 have a measured voltage of 56.8V to 57.8V, battery packs 1420 and 1422 have a specified delay 1402 of 450ms. Battery pack 1424 has a delay 1402 of 700ms before starting its discharge test. Battery packs 1418, battery packs 1420, battery packs 1422, and battery packs 1424 each attempt to join a battery system, such as battery system 100, in a parallel configuration. In some embodiments, the timeline sequencing of the bleed circuit 608 has the following order: delay 1402, measure primary (terminal) voltage 1404, measure auxiliary voltage 1406, test auxiliary contactor 1408, close primary contactor (and dwell time) 1410, bleed test A portion 1412, bleed test B portion 1414, and agree to engage decision 1416. In other embodiments, the bleed test B portion 1414 is not required before the battery pack receives the agree to engage decision. The bleed test portion A can be 100ms for each battery pack, and the bleed test portion B can be an added 50ms for each battery pack. The bleed test B portion 1414 may only be required for machines with particularly large capacitance, thereby requiring an extended test time. Battery pack 1418, battery pack 1420, and battery pack 1422 may all engage the terminal bus after "agreeing to engage decision" 1416, because their respective measured terminal voltages (which may be measured in step 1204 of process 1200) are within the engagement voltage, such as 1.00V of another battery pack on the terminal bus. However, battery pack 1424 has an exemplary terminal voltage of 56.0V and is outside the engagement voltage. Therefore, battery pack 1424 waits in a "standby" mode to engage when the battery pack becomes safe (e.g., the SOC of the other battery packs 1418, 1420, 1422 has dropped to within 1.00V).

[0063] refer to Fig.15, a parallel example 1500 of a discharge circuit sequence for discharging a battery pack (such as battery pack 1100) to engage a parallel process of a battery system 100 is shown according to an exemplary embodiment. In the parallel example 1500, there is only one battery pack (i.e., non-parallel), and the system does not have a terminal energy storage device, such as a capacitor or another battery pack. At time 1502, a battery management system (e.g., BMS1118) receives a discharge enable signal. At 1504, BMS1118 waits a predetermined amount of time based on the battery pack voltage 1510 according to the discharge sequencing table 1000. After a predetermined amount of time from when the discharge enable signal is received at time 1502, at time 1506, BMS1118 turns on its discharge circuit to test whether there is a terminal energy storage device on the terminal bus. Then, at time 1508, if the BMS 1118 finds that it is safe, the BMS 1118 turns on all contactors (e.g., auxiliary contactor 1102 and main contactor 1104) to engage the terminals. In the parallel example 1500, because there is no terminal voltage at time 1508, meaning that there is no other capacitor or battery on the terminal, it is determined to be safe (i.e., engagement is agreed).

[0064] refer to Fig.16 , a parallel example 1600 of a discharge circuit sequence for discharging a battery pack (such as battery pack 1100) to engage a parallel process of a battery system 100 is shown according to an exemplary embodiment. In the parallel example 1600, there is only one battery pack (i.e., non-parallel), and the system (e.g., equipment coupled to a terminal bus) has a terminal energy storage device, such as a capacitor or another battery pack. At time 1602, a battery management system (e.g., BMS1118) receives a discharge enable signal. At 1604, BMS1118 waits for a predetermined amount of time based on the battery pack voltage 1610 according to the discharge sequencing table 1000. Once the predetermined delay starting from when the discharge enable signal is received at time 1602 ends, at time 1606, BMS1118 turns on its discharge circuit to test the presence of a terminal energy storage device (such as a battery pack or capacitor). Next, at time 1608, if the BMS 1118 determines that it is safe, the BMS 1118 turns on all contactors (e.g., auxiliary contactors 1102 and main contactors 1104) to engage the terminals (e.g., positive terminal bus 122). In the parallel example 1600, because the discharge circuit is able to discharge the terminal voltage 1612, it means that the connected terminal energy storage device is a capacitor rather than a battery, so it is considered safe (i.e., it agrees to engage).

[0065] refer to Fig.17, a parallel example 1700 of a discharge circuit sequence for discharging a battery pack (such as battery pack 1100) to engage a parallel process of a battery system 100 is shown according to an exemplary embodiment. In the parallel example 1700, there is only one battery pack (i.e., non-parallel), and the system has a terminal energy storage device. At time 1702, a battery management system (e.g., BMS1118) receives a discharge enable signal. At 1704, BMS1118 waits for a delay time period based on the battery voltage 1710 according to the discharge sequencing table 1000. After the predetermined delay has passed, at time 1706, BMS1118 turns on its discharge circuit to test the terminal energy storage device connection to the terminal bus. Then, at time 1708, if BMS1118 finds that it is safe, BMS1118 turns on all contactors (e.g., auxiliary contactor 1102 and main contactor 1104) to engage the terminal bus. In the parallel example 1700, it is determined to be safe (i.e., engagement is agreed) even though the bleeder circuit cannot bleed the terminal voltage (indicating the presence of another battery pack). Because the voltage of the battery pack 1100 is within the terminal blocking voltage, the engagement of the battery pack 1100 is safe. For example, when the BMS 1118 turns on all contactors to engage the terminal bus, the battery pack voltage 1710 is 57.2V and the terminal voltage 1712 is 57.8V.

[0066] refer to Fig.18 , a parallel example 1800 of a discharge circuit sequence for a parallel process for engaging a battery system 100 for discharge is shown according to an exemplary embodiment. In the parallel example 1800, there are two battery packs without CANbus network communication. At time 1802, each BMS of the two battery packs receives a discharge enable signal. At time 1804, each BMS waits for a predetermined amount of time according to the discharge sequencing table 1000 based on the battery pack voltage 1814 of the first battery pack and the battery pack voltage 1816 of the second battery pack. Because the battery pack voltages 1814, 1816 are different, each battery pack has its own corresponding delay. After the delay for the first battery pack ends, at 1806, the first BMS turns on the discharge circuit for the first battery pack to test the terminal energy storage device. At time 1808, if the first BMS finds that it is safe, it turns on all contactors (e.g., auxiliary contactor 1102 and main contactor 1104) to engage the terminals.

[0067] In the parallel example 1800, it is determined that it is safe to engage the first battery pack (i.e., agree to engage) because there is no terminal voltage at time 1808, which means that the battery pack is the first to engage the terminal bus. At time 1810, the delay for the second battery pack ends, and the second BMS turns on the discharge circuit of the second battery pack to test the terminal energy storage device. Then at time 1812, if the second BMS determines that its engagement is safe, it turns on all contactors of the second battery pack to engage the terminals. It is found that the engagement of the second battery pack is also safe because the battery pack voltage 1816 is within the terminal latching voltage despite the absence of discharge terminal voltage. The terminal voltage 1818 will then be adjusted based on the battery pack voltages 1814, 1816.

[0068] refer to Fig.19 , a parallel example 1900 of a discharge circuit sequence for a parallel process for two battery packs to engage the battery system 100 for discharge is shown according to an exemplary embodiment. In the parallel example 1900, there are two battery packs without CANbus network communication, but in other embodiments, there may be more than two battery packs. At time 1902, each BMS of the two battery packs receives a discharge enable signal. At time 1904, each BMS waits for a predetermined amount of time according to the discharge sequencing table 1000 based on the battery pack voltage 1914 of the first battery pack and the battery pack voltage 1916 of the second battery pack, each battery pack having its own corresponding delay. Once the delay for the first battery pack ends, at 1906, the first BMS turns on the discharge circuit for the first battery pack to test the terminal energy storage device. At time 1908, if the first BMS finds that it is safe, it turns on all contactors (e.g., auxiliary contactor 1102 and main contactor 1104) to engage the terminal bus.

[0069] In the parallel example 1900, it is determined that it is safe to engage the first battery pack (i.e., agree to engage) because there is no terminal voltage at time 1908, which means that the battery pack is the first to engage the terminal bus. At time 1910, the delay for the second battery pack ends, and the second BMS turns on the discharge circuit of the second battery pack to test the terminal energy storage device. At time 1912, if the second BMS determines that its engagement is safe, it turns on all contactors of the second battery pack to engage the terminals. It is found that the engagement of the second battery pack is unsafe because the discharge circuit of the second battery pack cannot discharge the terminal voltage, and the battery pack voltage 1916 is outside the terminal lockout voltage. For example, the lockout voltage is + / -1.00V, the terminal voltage 1918 is 57.5V and the battery pack voltage 1916 of the second battery pack is 55.1V, which means that the second battery pack is not within the lockout range of the terminal. The second battery pack will continue to monitor (eg, periodically or continuously) the voltage on the terminal bus and will remain in the standby mode until the voltage on the terminal bus falls within the latching voltage range, such that the second battery pack can then safely engage the terminal bus.

[0070] refer to Fig. 20 , which shows a parallel connection process that can be used in a battery system 100 (such as reference Fig.21 The charging sequence table 1000 may include a delay column 2002, a voltage range column 2004, and a sequence number column 2006. The voltage range column 2004 may be in the example of reference Fig.21 The process 2100 is described to find the delay (in ms) corresponding to the measured terminal bus voltage value during step 2110. For the charging sequencing table 2000, the standard lockout voltage is set to + / -1.00V, and the incremental delay time for the next sequence is increased by 250ms. In some embodiments, active CANbus communication between the BMS and the charger within each battery pack is required in order to charge any battery pack. In some examples, if the BMS does not have a properly functioning CANbus communication network, the BMS may not allow the battery pack to charge.

[0071] refer to Fig.21, a flow chart of an automatic process 2100 for determining the ability of a battery pack to be connected in parallel with other battery packs using a bleeder circuit charge is shown. Process 2100 begins by performing a CAN source address request process to determine whether there are other batteries on the CANbus network. Step 2102 may occur a predetermined time (such as 1.5 seconds) from the start of the charge enable signal input, which should be exactly the same amount of time regardless of whether another battery is found to be present. The presence or absence of any other CAN-enabled battery is recorded and potentially performed by a battery system (e.g., battery system 100). Process 2100 proceeds to step 2104, where the battery pack determines whether there is another battery on the CANbus, which determination may be performed by a BMS (such as BMS 714). If another battery is found to be present at step 2104, process 2100 includes waiting for a predetermined amount of time at step 2118 and then proceeding to step 2106. For example, if another battery is present but it is not connected via CAN, then during the wait, the other battery will time out and then allow the CAN-enabled battery to begin charging.

[0072] Conversely, if there is no other battery on the CANbus, the process 2100 immediately proceeds to step 2106. At step 2106, the main contactor (e.g., main contactor 702) voltage sense potential is measured, which is also the terminal bus voltage. At step 2108, the BMS 714 determines whether the measured voltage is greater than or less than a predetermined value. If it is found in step 2108 that the voltage is greater than the predetermined value, then at step 2116, the BMS 714 issues a soft fault and may require a charge enable reset cycle. For example, if the predetermined value is 60V and the measured value is greater than 60V, the BMS 714 may issue a soft fault indicating that a "high sub-bus voltage" is present.

[0073] However, if the voltage is found to be less than the predetermined value in step 2108, the process 2100 proceeds to step 2110, where the BMS 714 delays the time based on the measured battery voltage according to the charging sequencing table (e.g., charging sequencing table 2000). After the delay time starts from step 2110, the process 2100 continues by turning on the bleeder circuit (e.g., bleeder circuit 608) at step 2112 and measuring the percentage change in the terminal bus voltage. Once the change in the terminal bus voltage is measured, the process 2100 proceeds to step 2114 to start Fig. 22 Process 2200 shown in .

[0074] refer to Fig. 22, a flow chart of an automatic process 2200 for determining the ability of a battery pack to engage in parallel with other battery packs using bleeder circuit charging is shown according to an exemplary embodiment. As described above, process 2200 begins at the end of process 2100. In some embodiments, process 2200 begins at step 2202, and the BMS 714 determines whether the percentage change in the terminal bus voltage after the voltage turns on the bleeder circuit 608 in step 2112 of process 2100 is greater than a predetermined value. If the percentage change is found to be greater than the predetermined value, process 2200 proceeds to step 2204, where the battery pack engages the terminal bus (by turning on the main contactor) and changes its mode to "charging". For example, if the percentage change is greater than 15% after 100ms, the main contactor 702 turns on, and the battery pack 600 engages the positive terminal bus 122 and enters the "charging" mode. In some embodiments, a 10-second charger timeout countdown begins after entering the "charging" mode, and if a charger is not present, a soft fault is issued and a charging enable cycle is required.

[0075] If the percentage change is found to be less than a predetermined value in step 2202, the process 2200 proceeds to step 2206, where the BMS 714 continues the bleeder circuit operation for an additional predetermined time. In some embodiments, by the end of 100 ms, the predetermined value is 15%, and the additional predetermined time for the bleeder circuit operation to continue is 50 ms, giving a total of 150 ms. Once the additional predetermined time for the bleeder circuit operation is over, then at step 2208, the BMS 714 may again determine whether the percentage change is now greater than the predetermined value. If, after the additional time, the percentage change is now large enough, the process 2200 proceeds to step 2204, where the battery pack engages the terminal bus and transitions to "charge" mode. If, after step 2208, the percentage change is still not large enough, the process 2200 proceeds to step 2210, where the BMS 714 continues to determine whether there are other batteries on the CANbus. Process 2200 includes changing the mode to "Standby Discharge" in communication mode at step 2212, and then following the charging sequence to engage the terminal bus once the battery pack is within the lockout voltage of any other battery pack on the CANbus (i.e., there are 2 or more battery packs) at step 2214. If there are no other battery packs (i.e., there is only the battery pack attempting to engage), process 2200 includes changing the mode to "Communication" mode at step 2216, and then issuing a soft fault (e.g., a soft fault requiring a charge enable cycle) at step 2218. In some embodiments, it is necessary to restart the charge cycle to prevent the battery pack from attempting to charge blindly without sending a CAN message to the charger.

[0076] refer to Fig.23, shows an automatic process 2300 for determining the ability of a battery pack to be connected in parallel with other battery packs using a bleeder circuit charge according to an exemplary embodiment. Process 2300 begins at step 2302, where the battery pack performs a CAN source address request process to determine whether other batteries are present on the CANbus network. Step 2302 may occur a predetermined time (e.g., 1.5 seconds) from the start of the charge enable signal input, which predetermined time may be selected to be the same in amount of time regardless of whether any other battery is found to be present. The presence or absence of any other CAN-enabled battery is recorded. Process 2300 then includes determining whether another battery is present on the CANbus at step 2304, which may be performed by a BMS (such as BMS1118) of the battery pack 600. If at step 2304, BMS1118 finds that another battery is present, process 2300 includes waiting for a predetermined amount of time at step 2322 and then proceeding to step 2306. For example, if another battery is present but it is not connected via CAN, the other battery will time out during the wait period and then allow the CAN-enabled battery to charge.

[0077] On the contrary, if there is no other battery on the CANbus, the process 2300 immediately proceeds to step 2306. At step 2306, the process 2300 includes measuring the main contactor (e.g., main contactor 1104) voltage sensing potential (i.e., terminal bus voltage). In some embodiments, at step 2308, the BMS1118 makes a measurement and then determines whether the measured voltage is greater than or less than a predetermined value. If it is found in step 2308 that the voltage is greater than the predetermined value, the process 2300 continues to step 2320, and a soft fault is issued and a charge enable reset cycle is required. For example, if the predetermined value is 60V and the measured value is greater than 60V, the process 2300 (e.g., using the BMS 1118) can issue a soft fault indicating that a "high-side sub-bus voltage" is present, and then a charge enable reset cycle of the battery pack may be required. However, if in step 2308 the BMS 1118 finds that the voltage is less than a predetermined value, the process 2300 continues to step 2310 and includes measuring the auxiliary (contactor) voltage sense potential. At step 2312, the process includes checking whether the measured auxiliary voltage is zero, which may indicate a problem with the main contactor or a fault in the BMS 1118. If the auxiliary voltage is not 0V, a soft fault is issued at step 2318, indicating that there may be a main contactor or BMS fault. However, if the auxiliary voltage is 0V, the process 2300 proceeds to step 2314, turns on the bleeder circuit (e.g., bleeder circuit 608) and measures the current of the battery pack for a predetermined period of time. The process ends at step 2316 and proceeds to Fig.24 Process 2400 is shown.

[0078] refer to Fig.24 , shows an automatic process 2400 according to an exemplary embodiment, which is used to determine the ability of a battery pack to be connected in parallel with other battery packs using a discharge circuit charge. Once the battery pack current is measured in step 2314 of process 2300, at step 2402, the BMS1118 determines whether the current exceeds a predetermined amount. For example, the battery current of 10.0ms can be measured and the current is checked to see if the absolute value of the current is greater than 1A current. If the battery pack current exceeds the predetermined amount, the process 2400 proceeds to step 2424, where the BMS 1118 issues a soft fault, indicating that there may be an auxiliary contactor and / or auxiliary voltage sensing fault. If the current measured in step 2314 is lower than the predetermined amount, the process 2400 proceeds to step 2404, where the BMS1118 turns on the main contactor and measures the battery pack current again for a predetermined period of time.

[0079] At step 2406, the BMS1118 may determine whether the current measured in step 2404 exceeds a predetermined amount. For example, the battery current may have a 1A limit. Therefore, the BMS1118 needs to verify that the absolute value of the current exceeds a current greater than 1A. Process 2400 includes: at step 2422, if the battery pack current exceeds a predetermined amount, a soft fault is issued, indicating that a discharge circuit 608 failure may have occurred. If the current measured in step 2406 is lower than a predetermined amount, the process 2400 proceeds to step 2408 and includes delaying the time based on the measured voltage according to a charging sequencing table (e.g., charging sequencing table 2000). At step 2410, the process 2400 includes engaging the discharge circuit and measuring the percentage change in the terminal bus voltage (i.e., the main voltage sensing potential).

[0080] At step 2412, process 2400 includes determining whether the percentage change in the terminal bus voltage after operating the bleeder circuit 608 is greater than a predetermined value, which may be performed by the BMS 1118. If the percentage change is greater, process 2400 proceeds to step 2414 by engaging the terminal bus (by closing the auxiliary contactor) and changing the mode to "charge". In some embodiments, if the percentage change is greater than 15% within 100 ms, the auxiliary contactor 1102 is closed, and the battery pack 600 engages the positive terminal bus 122 and enters the "charge" mode.

[0081] Still reference Fig.24, conversely, if in step 2412 the percentage change is found to be below a predetermined value, the process 2400 proceeds to step 2416 and continues the bleeding circuit operation for an additional predetermined time. In some embodiments, the predetermined value is 15% within 100 ms, and the additional predetermined time for which the bleeding circuit operation is continued is 50 ms, giving a total time value of 150 ms. At step 2418, the process 2400 includes determining whether the percentage change is greater than the predetermined value after the additional time. If the percentage change is large enough after the additional bleeding circuit operation, the process 2400 proceeds to step 2414 by engaging the terminal bus (e.g., the positive terminal bus 122) and changing the mode to "charging". Conversely, if the percentage change is still too low after the increased time of operating the bleeding circuit, the process 2400 includes changing the battery mode to "standby charging" in the communication mode at step 2420.

[0082] In some embodiments, the goal of the parallel system in charging mode is to rebalance all battery packs in the parallel configuration (e.g., as described in reference Figure 4 The battery pack 402, battery pack 404, battery pack 406, and battery pack 408 are described. In summary, during the charging mode for parallel engagement, the battery (e.g., battery pack 402) can start its positive terminal bus sequence with opposite timing based on the individual voltage of battery pack 402. According to an exemplary embodiment, after checking whether there is a terminal bus voltage, if there is no terminal bus voltage, the battery pack will engage, and if there is a terminal bus voltage, it will attempt to discharge the circuit. Then, if the circuit does discharge, the battery pack can engage the parallel system, and if the circuit does not discharge, an alarm can be generated. All batteries in charging mode can issue a constant current (CC) command until any one of the batteries issues a constant voltage (CV) command. Once a battery issues a CV command, all other batteries can also enter CV mode. In some embodiments, the CV command comes from the weakest battery in the parallel battery system. This is possible because the batteries can negotiate to suspend or terminate charging, or later restore to the "highest power" battery that performs better in the system. In this battery system, any one battery can command the charger. Additionally, an initial low charge rate may be requested to determine how many chargers are present on the bus. Two or more measurements may be taken and then an updated charge rate may be used with a multiplier. There may be a string of commands sent by the digital communication protocol to accurately assess how many chargers are connected to the parallel system.

[0083] The various methods and systems described herein can allow battery systems in various types of equipment (e.g., outdoor power equipment, indoor power equipment, portable field equipment, military vehicle applications, etc.) to safely utilize parallel battery packs and prevent damage to the health of the individual battery packs when they attempt to engage the system in a parallel configuration. The timed entry of the parallel configuration that turns on the bleeder circuit and engages other battery packs (as described in processes 1200, 1300, 2100, 2200, etc.) can advantageously allow the battery pack to avoid current inrush that is detrimental to the functionality of the battery pack. The delays in the sequencing table may also become more useful as the battery pack ages. In addition, having a dual-axis contactor prevents physical shock in one direction (e.g., axial to the contactor) from causing both the primary contactor and the auxiliary contactor to turn on due to the same shock load. Reference Figure 21 to Figure 24 The charging capability of the described method can help rebalance all battery packs with unique charge states in a parallel configuration. When the internal resistance in the battery packs is also low, a parallel configuration with unbalanced battery packs can lead to destructive situations such as a transient 2000 amp current from one battery pack to another. By preventing damaging transient currents in the battery packs of the system, the battery life of the battery system in different types of equipment can be extended.

[0084] Although this specification contains many specific implementation details, these details should not be understood as limitations on the scope of the content claimed, but should be regarded as descriptions of features peculiar to a particular implementation. Certain features described in this specification in the context of different implementations may also be implemented in combination in a single implementation. On the contrary, the various features described in the context of a single implementation may also be implemented in multiple implementations individually or in the form of any suitable sub-combination. In addition, although certain features may be described above as acting in certain combinations and even initially claimed as such, one or more features in the claimed combination may be removed from the combination in some cases, and the claimed combination may involve a sub-combination or a variation of a sub-combination.

[0085] It should be understood that although the use of words such as "desirable" or "suitable" used in the above description indicates that the feature described so far may be more desirable, the feature may not be required, and embodiments lacking the feature may be considered to be within the scope of the present invention, which is defined by the appended claims. When reading the claims, when words such as "one", "an", or "at least one" are used, it is not intended to limit the claim to only one item unless explicitly stated to the contrary in the claim.

[0086] It should be noted that certain paragraphs of the present disclosure may reference terms such as "first" and "second" in conjunction with sides and ends, etc., to identify or distinguish one from another, or one from multiple others. These terms are not intended to relate entities (e.g., first side and second side) only in time or according to sequence, although in some cases, these entities may include such relationships. These terms also do not limit the number of possible entities (e.g., sides or ends) that can operate within a system or environment.

[0087] As used herein, the terms "coupled," "connected," and the like refer to the joining of two components directly or indirectly to one another. Such joining may be fixed (e.g., permanent) or movable (e.g., removable or releasable). Such joining may be achieved by the two components, or the two components and any additional intermediate components, being integrally formed as a single unitary body with one another, or by the two components, or the two components and any additional intermediate components, being attached to one another.

[0088] As used herein, the term "circuit" may include hardware configured to perform the functions described herein. In some embodiments, each corresponding "circuit" may include a machine-readable medium for configuring the hardware to perform the functions described herein. The circuit may be embodied as one or more circuit components, including but not limited to processing circuits, network interfaces, peripherals, input devices, output devices, sensors, etc. In some embodiments, the circuit may take the form of one or more analog circuits, electronic circuits (e.g., integrated circuits (ICs), discrete circuits, system-on-chip (SOC) circuits, etc.), telecommunications circuits, hybrid circuits, and any other type of "circuit". In this regard, a "circuit" may include any type of component for implementing or facilitating the implementation of the operations described herein. For example, a circuit as described herein may include one or more transistors, logic gates (e.g., NAND, AND, NOR, OR, XOR, NOT, XNOR, etc.), resistors, multiplexers, registers, capacitors, inductors, diodes, wiring, etc.).

[0089] "Circuit" can also include one or more processors that are communicatively coupled to one or more memories or memory devices. In this regard, the one or more processors can execute instructions stored in the memory, or can execute instructions that are otherwise accessible to one or more processors. In some embodiments, the one or more processors can be embodied in various ways. The one or more processors can be constructed in a manner sufficient to perform at least the operations described herein. In some embodiments, the one or more processors can be shared by multiple circuits (for example, circuit A and circuit B can include or otherwise share the same processor, and in some example embodiments, the processor can execute instructions stored or otherwise accessed via different areas of the memory). Alternatively or additionally, the one or more processors can be constructed to perform or otherwise perform certain operations independently of one or more coprocessors. In other example embodiments, two or more processors can be coupled via a bus to implement independent, parallel, pipelined or multithreaded instruction execution. Each processor can be implemented as one or more general-purpose processors, application-specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), digital signal processors (DSPs), or other suitable electronic data processing components configured to perform instructions provided by memory. The one or more processors may take the form of a single-core processor, a multi-core processor (e.g., a dual-core processor, a triple-core processor, a quad-core processor, etc.), a microprocessor, etc. In some embodiments, the one or more processors may be external to the device, for example, the one or more processors may be remote processors (e.g., cloud-based processors). Alternatively or additionally, the one or more processors may be internal to the device and / or local to the device. In this regard, a given circuit or component thereof may be provided locally (e.g., as part of a local server, a local computing system, etc.) or at a remote location (e.g., as part of a remote server such as a cloud-based server). To this end, a "circuit" as described herein may include components distributed across one or more locations.

Claims

1. A battery system, comprising: a first battery pack coupled to the terminal bus and providing a voltage to the terminal bus; a second battery pack coupled to the terminal bus, the second battery pack comprising: Positive terminal and negative terminal, a bleeder circuit selectively coupled to the negative terminal, One or more contactors, one or more battery cells selectively coupled to the positive terminal and selectively coupled to the terminal bus based on the position of the one or more contactors, and A battery management system, the battery management system being configured to: measuring the voltage of the terminal bus coupled to the bleeder circuit, the voltage corresponding to the output voltage of the first battery pack; determining whether the voltage of the terminal bus is less than a predetermined value; In response to determining that the voltage is less than the predetermined value, connecting the discharge circuit to the terminal bus to attempt to discharge the voltage of the terminal bus; In response to determining that the voltage of the terminal bus is not discharged by a predetermined threshold amount, determining whether the voltage of the terminal bus is within a lockout voltage range; and The battery cell is coupled to the terminal bus by closing the one or more contactors in response to determining that the voltage of the terminal bus is within the lockout voltage range. 2 . The battery system of claim 1 , wherein the battery management system is configured to change a mode of the second battery pack to communicate with a digital communication protocol to couple the second battery pack to the first battery pack. 3 . The battery system according to claim 2 , wherein the battery management system is configured to determine the presence of other battery packs connected to the digital communication protocol by performing a source address request process.

4. The battery system of claim 1, wherein the bleeding circuit of the second battery pack comprises a pre-charge relay positioned in series with the battery cell, a bleeding switch of the bleeding circuit, and the negative terminal.

5. A battery system, comprising: a plurality of battery packs in a parallel configuration; An independent battery pack, the independent battery pack comprising a discharge circuit, a main contactor, an auxiliary contactor, one or more battery cells and a battery management system, the battery management system being configured to: measuring a voltage of a terminal bus coupled to the bleeder circuit; measuring a voltage between the main contactor and the auxiliary contactor; delaying initiation of a test coupling the individual battery pack to the plurality of battery packs based on a preprogrammed value; turning on the discharge circuit of the independent battery pack to attempt to discharge the voltage of the terminal bus; as well as In response to the voltage of the terminal bus bleeding by a threshold amount, the independent battery pack is coupled to the plurality of battery packs. 6 . The battery system of claim 5 , wherein coupling the independent battery pack with the plurality of battery packs comprises closing the main contactor and closing the auxiliary contactor of the independent battery pack.

7. A battery system according to claim 5, wherein the battery management system is further configured to change the mode of the independent battery pack to communicate with a digital communication protocol to couple to the multiple battery packs once the discharge circuit discharges the voltage of the terminal bus, thereby indicating that it is safe for the independent battery pack to be coupled to the multiple battery packs.

8. The battery system of claim 7, wherein the battery management system is further configured to determine the presence of other battery packs connected to the digital communication protocol by performing a source address request process.

9. The battery system of claim 8, wherein the battery system is in a discharged state.

10. A method comprising: measuring a voltage of a terminal bus coupled to a bleeder circuit of an independent battery pack, wherein the independent battery pack includes the bleeder circuit, one or more contactors, one or more battery cell assemblies, and a battery management system; delaying, based on a predetermined value, the initiation of a test to couple the independent battery pack to a plurality of battery packs, wherein the plurality of battery packs are in a parallel configuration; turning on the discharge circuit of the independent battery pack to attempt to discharge the voltage of the terminal bus; as well as In response to the voltage of the terminal bus bleeding by a threshold amount, the independent battery pack is coupled to the plurality of battery packs.

11. The method of claim 10, wherein the method further comprises changing a mode of the independent battery pack to communicate with a digital communication protocol to couple to the multiple battery packs once the discharge circuit discharges the voltage of the terminal bus, thereby indicating that it is safe for the independent battery pack to couple to the multiple battery packs.

12. The method of claim 11, wherein the method further comprises determining the presence of other battery packs connected to the digital communication protocol by performing a source address request process. The method of claim 12 , wherein the plurality of battery packs are in a charging state.

14. The method of claim 10, wherein the one or more contactors include a main contactor and a secondary contactor. 15 . The method of claim 14 , wherein coupling the independent battery pack to the plurality of battery packs in the parallel configuration comprises closing the primary contactor and closing the auxiliary contactor of the independent battery pack.

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